Patients will be admitted to the gcrc for one day on two separate occasions. The patient will have evoked potentials and neuropsychological tests recorded and then be given nicotine gum or placebo. If the patient is a non smoking normal control not on neuroleptic medication, they will be given 60-90 mg of propanthaline prior to treatment with either placebo or nicotine gum. 10, 60 And 120 minute periods, evoked potential recording, neuropsychological tests and blood draws will be repeated.